Adventures in Babysitting
by Elantine
Summary: Peter is entrusted to babysit Morgan Stark for the first time, something he is entirely unprepared for. How exactly is he supposed to tell Mr. Stark that he lost his daughter? * Now an ongoing collection of oneshots surrounding Peter's adventures as a big brother *
1. Hide-N-Seek Champions

Peter Parker was many things.

Recent High School Graduate. Empire State University full-ride scholarship recipient. Genius.

Spider-man. Mentee to Tony Stark. A superhero in the making.

He was a nephew, a best friend, a boyfriend, a protégé. A big brother.

But at this precise moment, he was so much more than that.

Peter Parker was totally, utterly _screwed_.

This was largely because, of all the things he was, he was worst at being a big brother.

"Morgan!" he called for what had to be the fiftieth time, looking under the large couch in the middle of the Stark's living room for what had to be the fifteenth.

"Oh, man," Peter groaned when the bubbly two-year-old he was searching for was, unsurprisingly, still not hiding under that particular piece of furniture. He tugged on his hair as he slowly turned in place, gaze roving over the completely silent room. "I'm going to be in so much trouble when Mr. Stark gets home."

This was bad.

The Starks rarely went out without their precious, still extremely young daughter in tow. It had been a hectic two and a half years (give or take a few months) since the defeat of Thanos; and after Pepper had finally been able to tell Tony that she was pregnant, he had actually resolved to retire as much as the world would allow him and dedicate his time to their growing family. Peter was just happy that that somehow still included him—that with a wife and a baby, Tony still had time to mentor him. To be a _father_ to him.

And with great power comes great responsibility, so if Mr. Stark was going to treat him like the son he never had, that meant Peter had to treat baby Morgan like the little sister he never had.

So he had been pestering Tony and Pepper for months now, trying to get them to trust him enough to leave Morgan in his care while they took some time for themselves. To have a moment of true peace between just the two of them for the first time since Thanos destroyed half the universe (which, the Avengers were able to fix, of course, but that wasn't the point).

And this was the day. Mr. Stark had asked him a week ago to babysit his daughter while he and Pepper did… well, Peter wasn't really sure what they were doing. He just knew that Morgan had been entrusted to him for the evening, and he was _seriously_ messing that up.

If he didn't find Morgan before her parents got back in approximately 30 minutes, he was dead.

Well, not dead per se. But Mr. Stark would definitely never trust him again and he would be deemed the worst sort-of-big brother in the universe. And that was basically the same thing.

"Come on, Morgan! I give up. You can come out now!" It was back to her bedroom now, where he looked under her bed, in her closet, in the toy chest, in every conceivable hiding place he could imagine. But it didn't matter. Mr. Stark had warned him, but he hadn't listened.

"Ollie ollie oxen free!" he tried as a last ditch effort, but he knew it would be pointless. Morgan Stark was simply the best hide-n-seek player to ever live, and Peter should have heeded his mentor's warning and never agreed to play.

But come on! She was a tiny, adorable two-year-old! How could she be _that good_ at hiding?

Granted, the Stark's home was basically a mansion, with three-stories and roughly 8,000 sq. ft. of floor space. In an attempt at fairness, Peter and Morgan had agreed to stick to the main level for their game. However, Peter had the feelings that agreements made with toddlers were likely to hold little value, so he had painstakingly searched every floor, every room, every _crevice_ for the past two hours. Yet, still no Morgan.

It was insane.

He was _Spider-man_ for crying out loud! He caught criminals on the daily and occasionally even helped stop genocidal maniacs from destroying the universe. Finding a _two-year-old_ should not be nearly this difficult.

He was out of options and out of time. Mr. Stark would be here any minute and he would have to tell the man he looked up to most in the world that he had lost his only daughter in the span of four hours.

There was only one thing left to do.

" _Morgan_ ," Peter pled, dropping to his knees on the hardwood floor of the living room. "Please, Morgan. You gotta help me here. I give up. _Please_ come out now."

He ignored the sting of embarrassment that came with begging a two-year-old for mercy and continued to analyze his surroundings. Everything was still deathly still, his enhanced senses not picking up any sound or movement.

That was it. Nothing could save him now.

Sighing in resignation, Peter climbed to his feet again and dejectedly made his way to the kitchen. This was a stressful situation after all, and stressful situations called for copious amounts of food.

He checked his phone for the time as he strode into the kitchen.

 _8:47 p.m._

Thirteen minutes. He only had thirteen minutes left to live without the terrible shame of Tony Stark's disappointment.

His movements were sluggish as he grabbed a bowl from the cabinet and a box of cereal from the top of the fridge, the first edible thing he laid eyes on.

It was Coco Pebbles. Peter's favorite.

He knew that Mr. Stark kept that particular cereal in his house for solely that reason, which made his failures as a babysitter, and more importantly, a self-proclaimed honorary big brother, so much worse.

"Ugh," he moaned, shoveling a spoon-full of the delicious cereal into his mouth as soon as the milk had been poured. "Now I have to tell Mr. Stark that I lost his daughter in his own house and he'll never trust me to watch her again," he mumbled around his cereal, staring sightlessly into the depths of his bowl.

He was most certainly exaggerating, but come on—he was an eighteen-year-old who knew he was about to disappoint someone who's approval meant everything to him. Not to mention he had just temporarily misplaced his favorite toddler. Things were not looking good for him at the moment, and he only had approximately 11 minutes left to pity himself before he had to face the music.

He heaved another world-weary sigh before stuffing his face again. "I probably won't be allowed to play with Morgan at all anymore."

"No!"

Peter jumped in the chair, twisting around to face the cabinet above the refrigerator—the direction the small, panicked voice came from, where a head of messy, dark brown hair was poking out.

"Morgan!" the teen cried out, jumping to his feet, doomsday snack entirely forgotten.

"I sorry, Petta!" the young girl babbled as she attempted to clamber down from her hiding place. She had just crash-landed on top of the fridge when Peter reached her, pulling her down and placing her safely onto the chair that he had just vacated. "I don' want you to be in trouble. I's just playin'!"

Peter stared at her with wide, almost shell-shocked eyes. He had checked that cabinet—multiple times. He knew from experience that it was one of her favorite places to hide.

"Morgan," he asked the toddler hesitantly, watching her with narrowed eyes as she determinedly gnawed on his abandoned spoon as though she would disappear before his eyes again. "Were you up there the whole time?"

The toddler giggled, her green-eyes shining brightly at him as she took the spoon out of her mouth and started drumming a complex beat on the table. "Nuh uh."

"Nuh uh?" he asked before taking the spoon away from her, belatedly realizing that it was probably not something she should be playing with.

Morgan pouted, as she was prone to do, but didn't protest his thievery otherwise. "No," she clarified. Sort of.

Peter laughed, scooping the girl up into his arms and taking her back into the living room to wait for her parents. "Then where were you? I've been looking everywhere for you, Iron Baby!"

Morgan shrieked in joy, as she usually did when Peter called her by the nickname he had given her (which had been quickly picked up by the other Avengers, much to Peter's pleasure). "I know! I was hidin' from you!"

"But I looked everywhere!" Peter protested, gently tossing the toddler onto the plush couch. He waited for her giggling and bouncing to subside before asking, "How did you stay hidden that long?"

Morgan looked at him with wide eyes, worryingly still and silent for a long moment. She looked first to the left, then the right, as though she was making sure they were still alone. Peter just raised an eyebrow, waiting for the show she was putting on to end.

Eventually Morgan deemed the living room safe and motioned Peter forward with chubby hands. Once he was crouched in front of her, she leaned in even closer and asked, in what was perhaps supposed to be a whisper, but was actually a touch louder than normal, "Can you keep a secret?"

Peter made a big show of checking their surroundings again, looking all around the room before nodding and loudly whispering, "Pinky swear."

As soon as the ritual pinky-swearing was completed, a mischievous smile—one much too evil to be found on the face of a two-year-old—spread across Morgan's face. She leaned in even closer, as everyone knows the closer you are the more secret it is, and said, "F.R.I.D.A.Y."

Peter was only confused for a moment before comprehension dawned on him and he jumped back and explained, "F.R.I.D.A.Y. helped you win!"

Morgan simply nodded, looking entirely pleased with herself. "Uh huh."

F.R.I.D.A.Y. was, of course, always monitoring the Stark household, so it made sense that the AI was capable of tracking Peter's movements and warning the youngest member of the Stark family so she could relocate herself. It was completely plausible. He just couldn't believe that a _two-year-old_ had thought to use it to her advantage.

When Peter didn't say anything while he processed this new information, Morgan grew concerned that her brother was not a reliable confidant after all. "You can't tell Daddy, Petta. You promised!"

"Of course not!" Peter assured her, crouching in front of her once more so she could clearly see his grin. "We pinky-promised, remember?"

Morgan returned his grin, nodding enthusiastically. "Now we can both hide from Daddy whenever we want!"

Peter had just began contemplating the possibilities of such an arrangement when the Starks returned, their entrance made obvious by Tony's loud exclamation of, "Where's my girl?"

Morgan squealed and hopped off the couch, running as fast as her chubby legs would take her to the foyer where her parents waited. Tony was crouching with his arms wide-open, waiting for the incoming hug from his daughter who he was clearly relieved to see was still alive and well.

"Mommy! Daddy!" said girl cried as she darted under Tony's outstretched arms and launched herself at her mother.

Pepper, of course, was delighted to be the parent of choice for the evening, but Tony pouted, causing Peter to grin and step forward with his own arms open.

"Mr. Stark?"

Tony looked away from his embracing wife and daughter and immediately rolled his eyes and stood up. "I'm alright, thanks kid."

"Aw, come on, Mr. Stark," Peter goaded, stepping forward. "We were both so good!"

Tony scoffed, but reached out to pull Peter into a quick one-armed hug. "I really doubt that, Spiderling."

He stepped back from the hug, but kept one arm around Peter as they turned to face the other members of their little family. "What do you think Pepper? Were they good?"

Pepper, who was holding her jabbering daughter, smiled and moved to leave the foyer. "I don't know. Let's see, shall we?"

They moved as one through the living room, making sure that nothing had been destroyed in their absence. When everything checked out, Pepper smiled down at her daughter. "It looks like you were a good girl for Peter after all, darling." Morgan only giggled happily in response, and Pepper turned to Peter and said, "Thanks again for watching her for us Peter. We really appreciate it."

"Oh, no problem!" Peter said, feeling like he could breathe easily for the first time in an hour. The Starks were back, Morgan had been found, nobody had died, nothing was broken. It had been a good night. But he wasn't about to push it. "Well," he said, grabbing his backpack that was waiting by the couch, "I'll just head out then."

"Not so fast," Tony said in a tone of voice that instantly made Peter freeze.

Peter turned slowly, internally cringing. He knew that voice. And sure enough, Mr. Stark was making the face that usually accompanied it. The one he always made when he thought they were hiding something from him. It was what Peter privately referred to as his Dad Face, and it was truly fearsome.

He was so busted.

"F.R.I.D.A.Y."

"Yes, Mr. Stark?" the AI responded while Peter started praying.

"Did anything of note happen while we were gone?"

Peter held his breath, not daring to make eye contact with Mr. Stark while he waited on F.R.I.D.A.Y to rat him out for temporarily losing Morgan… for two and a half hours.

Did Peter mention that he was _so dead_?

"No, Mr. Stark. There are no incidences to report."

Peter almost couldn't believe it and he audibly breathed in relief, probably not helping him seem less guilty. Morgan, however, smiled angelically at Peter, and he imagined that if she knew how to wink at him, she would have in that moment.

"Daddy! Daddy!" she cried after F.R.I.D.A.Y. gave the all-clear, clambering out of her mother's arms and running across the room into her father's.

Tony smiled at his daughter, though he still seemed to be on edge, as though he was waiting to find out that something catastrophic had happened in his short absence, despite everything seeming perfectly fine. "What is it sweetheart?"

"Petta and I had soooooooooo much fun! Can he watch me again?"

Tony pouted theatrically. "Aw, really? We let the kid watch you one time and now he's the only one you want to play with?"

Morgan chortled and grabbed her father's face to smush it between her chubby hands. "Don' be silly, Daddy! I wanna play with you too!"

"Well," Pepper said, moving toward the staircase with a soft smile, "you can all play, but I'm going to bed. Goodnight darling!" she called out, blowing the still-rambunctious toddler a kiss before ascending the stairs.

After everyone had called out their goodnights, Morgan turned back to her father with her normal, face-splitting smile. "So we play now, Daddy?"

Tony sighed dramatically, but agreed. "Yes, Morgan, we can play now. But just one game."

"Yay!" the girl cheered, clapping excitedly before she squirmed out of her father's arms to run to Peter. "We play hide-n-seek?"

Tony narrowed his eyes at his kids, knowing a trap when he saw one. "Morgan, you know that we can't play hide-n-seek. It takes way too long."

"Nuh uh," Morgan said, eyes too-wide as she rapidly shook her head. "I'll hide with Peter, so it'll be easier to find us. He not very good."

Peter bit his lip to hide his smile as Mr. Stark contemplated them, deciding if he should just agree to avoid the tantrum or press for a different game to spare himself the torture of playing hide-n-seek with his devious daughter. Peter wasn't going to let this opportunity pass him by that easily though. "She's been begging me to play all night, Mr. Stark. I think that we should play with her."

Tony considered it for only a moment more before reluctantly nodding with a sigh. "Fine. But just because I know that you are a terrible hide-n-seek player, Pete."

Peter nodded in agreement, only barely managing to hide his smile as Mr. Stark turned around and began to count to one hundred.

Morgan grinned up at him and took his hand as soon as the countdown began, running with him to their first hiding place of the night.

It was a challenge to keep the talkative child quite as they moved from spot to spot, but she was definitely a pro with F.R.I.D.A.Y. whispering to her from seemingly nowhere. No wonder no one was ever able to find her.

Peter's family had never been conventional, but that was okay with them. He had lost his parents and his uncle, and for a long time it had felt like it would only be him and May against the world. But things changed, and families didn't have to be nuclear to be meaningful.

He still had May, but he also had Ned and MJ, and Mr. Stark and Pepper, and the rest of the Avengers.

He also had someone he could consider a sister now, something he never thought he would have, but she was something he was unquestionably grateful for. Especially when they were curled up in a cabinet together, with Morgan asleep next to him while Mr. Stark grew increasingly more frustrated as he combed through their house, calling out for them in desperation all the while.

He couldn't remember the last time he played hide-n-seek, but he knew that it had never been as fun or as sweet as this.

 **A/N: I hope you liked this! It was just a fun idea I had, and I definitely needed some fluff in my life so. At this time, I'm thinking this will be a oneshot, but if I get a good response I would probably be happy to make it a series of short stories following Peter and Morgan's shenanigans. So if that's something you're interested in, please let me know!**


	2. Like Father, Like Son

Peter was trying _very hard_ not to freak out. And he was doing okay, if he could say so himself.

When Happy had showed up at his apartment to say that Mr. Stark needed his help ASAP, he had easily agreed and ran to his room to get his suit before Aunt May noticed he was leaving. When Happy said that wouldn't be necessary, he had hesitated, but still followed him down to the waiting car with little protest. On the ride over to the Stark residence, he had managed to annoy Happy enough to make him turn up the radio—no groaning about irritating kids or verbal request for him to stop talking, which was incredible progress.

Peter Parker was the epitome of chill right now. Whatever it was that Mr. Stark needed him for, he could handle it. He was super calm and super collected.

Except, he was _totally freaking out_. Like, seriously. Mr. Stark _never_ asked for his help, so this must be big. And he would be lying if he said he wasn't nervous, but he was almost eighteen now. He was basically adult, and he would act like one. Mr. Stark would definitely be impressed by his ability to remain calm under pressure; or he would be, if Peter could manage to keep his panicking internalized.

Peter wasn't surprised when Happy walked him to the door, but he was surprised when he started to leave as soon as Peter entered the spacious home of his mentor.

"Uh, Mr. Happy, uh sir—you're not coming in too?"

Okay, so the talking thing wasn't working so great right now, due to the aforementioned freaking out. But he had time to work on that before he found Mr. Stark. He just had to figure out what Happy was up to first.

Happy grinned at him, and if Peter wasn't nervous before, he definitely was then.

"No way, kid. I'm gonna find somewhere else to be until the storm clears."

"Storm?!" Peter's voice raised an octave in his initial panic, but he cleared his throat and tried to lower it to a more natural tone of voice when he said, "I mean, what storm?"

Happy laughed. Actually laughed. And then he walked back to the car, got in, and drove away with no explanation.

Peter needed no further confirmation. He was so screwed.

The teenage superhero audibly gulped as he entered the mansion, closing the door softly behind him. He carefully took in his surroundings as he moved through the foyer into the living room. Everything seemed to be in order—the Stark home was immaculate as always. Lavish furniture surrounded by high tech appliances and expensive art, the only sign that the room was even lived in was the section in the corner dedicated to baby Morgan's play pin and toys, though even all of her stuff was currently neatly put away in the color-coordinated bins.

More telling, though, was the fact that there was no sign of the Starks. The house was completely silent, as though it were holding its breath in anticipation of the supposed "storm."

Okay, so Peter's _not-really-but-kind-of-a-little-freaking-out_ had upgraded to _I'm-tottally-wigging-out-right-now_. If he was imagining the house doing anything other than being a house, he was letting this not-yet-a-situation get to him too much.

But he was Spider-man, and Spider-man wasn't afraid of suspiciously quiet houses. So he was gonna play it cool.

"Mr. Stark?!" he called out, trying to keep his voice neutral. "Mr. Stark, are you home?"

"Peter!" The response was almost immediate, and Peter whipped his head around to find his fellow Avenger racing down the stairs in a bigger hurry than he had ever seen him.

"What's going on? What's happening?" Peter was trying very hard to hold onto what was left of his cool, but that was proving difficult when he saw his normally perfectly composed mentor in such a state of disarray—he was wearing a wrinkled cat t-shirt with various stains, many recent-looking, and one long tear on the right sleeve; his hair was messy and missing it's normal gelled-look; he wasn't wearing shoes and was missing one sock; and his eyes held the wild, manic look of a crazed man.

Something was clearly wrong, but what was it? Aliens? Wizards—but the bad kind, not the fun, necklace wearing kind? Was Loki in a particularly bad mood? Had a genetically-mutated lion escaped the zoo and found solace in Mr. Stark's bed room? Was Mrs. Pepper mad at him?

A million different scenarios flashed through his hyperactive mind as he waited for Mr. Stark's answer, but nothing could have prepared him for the truth.

"I lost her, Pete. I looked away for one second, and she was just gone."

Mr. Stark was gripping his shoulders as though he wasn't sure if he wanted to pull him in for a hug or shake answers he didn't have out of him. Either way, Peter remained incredibly confused. "What? Who did you lose, sir?"

Tony's grip on Peter's shoulders tightened, and he was surprised to see real panic in his mentor's eyes. That's when it clicked, moments before Mr. Stark confirmed it. "Morgan. Pepper left me alone with her for the first time since she started crawling, and I've already lost her. It's been two hours, Peter. _Two hours._ "

This was... definitely not the disaster scenario Peter had imagined when Happy brought him here. But that didn't make it any less serious. His honorary baby sister was missing, and her father was currently freaking out even more than Peter was (something that he would remind himself to be proud of later), so that left Peter in charge of remaining calm and finding a solution—or rather, finding the rouge ten-month-old baby.

"She couldn't have gotten far, sir. Everything will be fine. Pepper will never even know." Peter tried to reassure his mentor, meeting his eyes solemnly so that he could see how serious he was.

"She always finds out, Peter. Always." Mr. Stark said this was uncharacteristic grave certainty, but finally released his shoulders and stepped away from him, seeming to gather himself now that he had someone else to ground him.

Peter couldn't deny that he was ecstatic that he was that person, but now was definitely not the time, so he straightened his shoulders and did what he did not do best—took charge of the situation. "Where did you see her last?"

It seemed like the obvious place to start, and Mr. Stark didn't appear to disagree as he immediately led him to his lab in the basement of his mansion.

Peter looked around the workshop with increasing trepidation. The lab of a retired superhero was definitely not the safest place for a child—half-finished weapons upgrades, random bits of scrap metal and loose wires, what looked like a new spider suit, which was super cool and he really needed to go check it out—

 _Focus, Peter. There's a baby on the loose._

With only a _mild_ bit of difficulty, Peter forced himself to look away from the new spidey suit, taking in the rest of the lab for clues.

"Uh, Mr. Stark. I can't help but notice that this may not be the, um… well, the best place for a kid to be."

He turned to face Tony just in time to see him roll his eyes. "You gotta give me more credit than that, kid. She was in that play pin thing over there," he pointed to an area I the corner of the lab that had was gated and had padded floors and toys strewn about it, "and I was _there_ ," he now indicated the table directly across from the Morgan Cage, "working on an upgrade to Barnes' arm. She was just playing, happy as can be, the entire time I kept an eye on her. But the second I turn away to grab a new part, she disappears. I can't figure out how she did it or where she could have possibly gone. I've looked _everywhere_."

Peter scratched his head, taking in the situation. "Doesn't FRIDAY have footage that could help? I thought this whole lab was under surveillance."

Tony crossed his arms and seemed to be visibly restraining himself from rolling his eyes again. "Of course she should, which is why I already checked. It was the first thing I did when I couldn't find her on this level."

"So… there was no footage?" Peter felt pretty stupid asking the question, but full understanding was kind of important give the situation. Luckily, Mr. Stark answered the question with only the slightest amount of sarcasm, which for him, was as good as a gentle explanation.

"No footage. She seems to be… going through some kind of glitch."

Peter's previous panic increased ten-fold as he asked, "FRIDAY can do that?"

Tony shrugged, though Peter knew him well enough to know that the tense set of his shoulders and the slight furrow of his brow along with the lack of a smirk indicated that he was unsettled by this as well. "Any tech can have glitches every now and then, but FRIDAY…"

"But FRIDAY shouldn't," Peter finished, trying to pull all of the pieces together as he analyzed the scene of the crime again. "Could the glitch be an indicator for some kind of security breach? I mean…" Peter hesitated, turning back to his mentor to take in his only mildly anxious expression before he asked, "You don't think someone _took_ her, do you?"

Mr. Stark immediately shook his head. "Not a chance. The only part of FRIDAY's programming that has been affected is the security footage of the house. There have been no perimeter breaches and no attempts at hacking into the system. Besides, I was in the room and I was turned away from her for thirty seconds, tops. I would have seen someone if she had been taken."

Peter nodded, visibly relaxing. Though he was still definitely confused. "Okay, so how did she get out of the pin?"

"No idea. The latch is kind of stupidly easy to lift, but Morgan's definitely too small to reach the it. And she can crawl now, but I'm pretty sure she can't climb this." Tony walked towards the gated-area that had held his daughter only an hour ago to show Peter what he meant. The teen crime-fighter dutifully focused his heightened senses on every detail he could find, most of it inconsequential, except—

"Are those track marks?"

Tony snapped his head down to look where Peter was pointing to the marks on the padded floor, only to deflate instantly. "Yeah, those are just from RoRo."

Peter furrowed his brow, "RoRo? You mean your Roomba?"

Tony nodded, "Yeah, that's what Morgan calls it. She loves the damn thing—that's why it was in there with her. She cried until I put it in with her, and I figured it could only help, considering the mess that kid leaves behind."

"Mr. Stark!" Peter exclaimed, the first puzzle piece fitting together in his mind's eye. "That's how she got out."

He watched as understanding dawned on Tony's face with more pride than he cared to admit. "She crawled onto the Roomba, which made her tall enough to unlatch the gate." Mr. Stark turned to him, smiling at him for the first time that day as some of his worry melted away. They at least knew how she got out, which was the first step to tracking her down. "Nice work kid. I can't believe I hadn't thought of that, but really. Good job."

Peter tried to keep his grinning to a minimum as he said, "Thanks Mr. Stark. Now we just need to figure out where she went."

Mr. Stark nodded, rubbing at his chin the way he usually did when he was working at a problem. "I think I know where to start."

* * *

"You were right to question FRIDAY's glitch," Mr. Stark told him as they entered the walled-off section of the lab that housed all of the security tech. The screens that usually played the real-time footage of the lab, Morgan's room, and the exterior of the house—the only areas of the property under constant surveillance—were all currently black. Mr. Stark strode over to the keyboard situated in front of the largest screen in the room, which also happened to be the only one currently working. "I had given a little thought to it before, but was too focused on trying to find Morgan as fast as possible that I didn't consider it enough. But it's not so much a _glitch_ as the security monitors have just been shut down—otherwise there would be other systems malfunctioning and FRIDAY would have immediately alerted me to the breach. Not to mention the incredibly convenient timing of it all."

Peter nodded, though Tony couldn't see him from where he stood behind his shoulder, watching him type at the keypad almost furiously. "So, you _do_ think that someone has hacked into the FRIDAY?"

Tony scoffed, his mouth pulling up into a half-smirk as he said, "No. I think _FRIDAY_ has shut down the monitors herself."

"Why would she do that?" Peter asked, his brow furrowed in thought. The AI was _extremely_ reliable. He couldn't imagine her doing something like shutting down one something so important.

"FRIDAY is one of the most advanced AI in the world, Pete. Which has both its good and bad qualities," he answered, still not looking away from the screen. "She's formed quite an attachment to the kid, so she's subjecting herself to the whims of an infant far more than she should be."

"You… you mean FRIDAY _helped_ Morgan get out of the pin and is now letting her cruise around the house undetected just because she thought that's what Morgan wanted?" Peter felt crazier and crazier as his question fell from his mouth, but Mr. Stark was unfazed.

"Yup. But luckily, I'm still the boss. So all it takes is a little manual labor and TLC to get the monitors back up and widen the surveillance to the whole house and… bingo," Mr. Stark finished typing with a flourish as the previously-blank screens came to life just in time to see Morgan roll past the camera that was recording the living room. "Yeah, FRIDAY is _so_ getting an update after this."

Mr. Stark jumped up from his chair to race back upstairs, Peter hot on his heels.

"How did she get up the stairs?" Peter asked incredulously as they climbed up said stairs, looking around in awe for some sign of Baby Stark's great escape.

"Ramps," Tony answered, wrenching the door to the ground floor open. "They pop out of the wall. For the Roomba my daughter is currently joyriding on."

Said daughter was blessedly still doing doughnuts in the living room when they got there, and she screeched in joy when she saw them. "Dada!" she cried, banging her fists on the Roomba the way she did whenever she got excited.

Tony breathed a sigh of relief before swooping down to pick up his daughter. "Morgan? What did you think you were doing?" he demanded, holding her up in front of his face to do a full health evaluation.

Peter couldn't resist laughing out loud when the ten-month-old, who was still far too young to understand most of the English language or read the tone of a room, giggled and smoosed her stressed-out father's face between her tiny hands.

His outburst drew said-infants attention, and she grinned at him, flashing the few teeth she had. "Petta! Petta!" she yelled, his name coming out garbled and unclear, but he easily recognized it by now. He walked over to her and she stretched out her little arms for him to pick her up, which he did after Tony nodded at him in permission.

"Heeeeeey, Iron Baby," he cooed at her. "You gave us quite the scare, you know."

"She did?"

Peter and Tony both whirled around in shock, having been too preoccupied with making sure Morgan was okay to notice that the front door had opened and Pepper had returned from Stark Industries. She was now watching them from the hallway between the living room and foyer, her expression expectant as she took in her little family.

Peter carefully kept his mouth shut and looked back down at Morgan, pretending to be too engrossed with her to answer.

"She was just crawling a little too close to the kitchen, but we have everything under control. Obviously," Mr. Stark said, walking over to his wife and enveloping her in a hug. "How are things going at the office?"

"Mmmhmm," Pepper hummed, unconvinced but deciding to let it go. For now. "Everything was running fine, so it was just a quick check. Peter," she said, moving her attention to the suddenly tense teen, "I didn't know you would be stopping by today."

He carefully avoided looking at Mr. Stark as he answered, "Oh, uh, yeah. I stopped by to ask Mr. Stark a few questions about my physics homework."

Pepper seemed to buy it, if her easy smile was anything to go by, and she approached where he was currently bouncing Morgan on his hip. "Were you a good girl while Mommy was gone?" she cooed at her daughter, gently extricating her from Peter's hands to hug her to her chest.

Morgan giggled, looking up at her mother in joy as she answered, "No!"

Peter couldn't help it. He burst out laughing, Mr. Stark quickly joining him as they doubled over with laughter.

Pepper, however, was concerned. "No?" she questioned, her brow furrowed as she looked down at her happily-gurgling child.

"Kids," Tony said, still chuckling under his breath as he slung one arm around his wife and winked at Peter. "They say the darndest things."

"She was great, Mrs. Stark," Peter assured, saying it easily and with little guilt. It was true, after all. Though Morgan had nearly given both her dad and honorary big brother a heart attack with her daring escape from baby jail, she was always great. She was definitely the coolest baby Peter knew, anyway.

Of course, she was the only baby Peter knew. But still.

Pepper eyed them both cautiously, but soon relaxed. She had long ago learned that questioning everything that Tony (and especially Tony _and_ Peter) did was not worth the effort. Nothing was on fire and her daughter was happy and safe, so she would let them off the hook. "Are you staying for dinner, Peter? I can make you favorite. Homemade pizza, right?"

"Oh, yeah, that'd be great! Just let me check with Aunt May real quick," Peter said, hopping up from where he was leaning against the couch to get his phone out and call his Aunt.

"Go ahead and invite her too, Pete," Mr. Stark said, moving to take his daughter back from Pepper so she could take her shoes off and put her bag down before moving to the kitchen, presumably to start cooking. "I've been meaning to talk to both of you about where you want to go to college anyway."

Peter beamed at his mentor, "Sounds great, sir."

Tony rolled his eyes. "I've told you a million times, kid. Just call me Tony."

Pepper popped her head back into the living room just long enough to yell, "I think 'Dad' would be an acceptable substitution as well at this point."

Tony scoffed indignantly, but offered no verbal rebuttal.

Peter dutifully ignored both of them, though he felt his cheeks tinge pink as he dialed Aunt May's number.

He continued to make funny faces at Morgan throughout the short call, causing her to giggle uncontrollably all the while. After the call had ended and May had agreed to head to the Stark house for their family dinner, Peter moved to the kitchen to help Pepper cook while Tony kept Morgan occupied in the living room.

Pepper smiled at him, and happily accepted his help, blessedly not bringing up the whole "dad" thing again. He couldn't deny that Tony was the closest thing Peter had ever had to a father figure, excluding his Uncle Ben, but he wasn't just going to start _calling_ him that, even if it did carry some appeal. At least not yet.

For now, he was happy with this still relatively new family dynamic, especially with the addition of Morgan. He had never thought that he would have the opportunity to actually be a brother, given the circumstances that life had thrown at him; but time had a funny way of changing things, and this was one such example that Peter couldn't be happier about.


	3. Big Brother Protocol

Tony loved being a dad. He really did. There was nothing quite like the joy of seeing your child take her first steps, say her first word, or just smile at you with such complete adoration you know that you would do anything to preserve her happiness.

However, there were definitely some major downsides to parenthood as well.

"Morgan,.Morgan, you gotta calm down honey. It's alright," Tony cooed to his squalling eighteen-month-old daughter. She only cried louder in response, blubbering something into his shoulder.

"You don't think that she's just that upset about the _Easter Bunny_ do you?" Pepper asked as she rubbed soothing circles on Morgan's back. They were currently sequestered in a corner of the bustling mall they had taken their daughter to for her first experience with the Easter Bunny. Tony hadn't been a big fan of the idea—malls weren't exactly his idea of a fun place to take your family, considering the lack of security and plethora of other screaming children, but Pepper had insisted that this was a tradition that she intended to share with their baby.

It would seem, Tony thought as he glanced over his shoulder to see the bright pink, admittedly creepy man-sized rabbit pose for a photo with another child, that he was actually right for once.

"Yeah, Pep, if I had to guess, I would say it was the bunny with the manic smile and glazed eyes that scared her, not the pretzel stand."

Pepper gave him a reproachful look. "Not helping Tony."

Tony grimaced when Morgan screeched again, as if proving her mother right. As if he needed the reminder.

"I don't know what will help! She just won't stop crying," Tony said, consciously trying to keep his tone level despite his rising stress level. After a year and a half of being a parent, Tony was well-accustomed to crying infants, but it didn't make it any easier to deal with said infant having a meltdown in public.

"Brudda!" Morgan blubbered, raising her head up to look at him with tear-filled green eyes. "Brudda! Brudda!"

"What?" Pepper asked, smoothing Morgan's curly brown hair back from her face. "What do you want sweetie?"

"Bru…tha! Where… my… brutha?!" Morgan gasped out, emphasizing each word. Unfortunately, both Tony and Pepper were still at a loss.

"Brother?" Tony said, confusion only increasing as he realized that had to be what she was trying to say.

Morgan nodded exuberantly, burring her curly head back into his chest as she let out another shuddering cry.

"Brother?" Pepper asked, looking up at Tony before returning her gaze back down to her daughter. "But sweetie… you don't have a brother. You need to tell us what you want so we can help you."

That, as it turned out, was precisely the wrong thing to say to the distraught girl, as her crying only increased and she rapidly approached full-on tantrum mode. Morgan was quickly approaching her terrible twos, as evidenced by this going on fifteen-minute freak out.

Tony knew that she was upset and scared, and that she clearly wanted something to make her feel better. Usually either him or Pepper were able to calm her down and make her laugh long enough to get them out of Dodge, but not this time. The only thing they hadn't tried yet…

"Pete," Tony said, realization dawning on him a little slower than it should have. "You want Peter, right Morgan?"

Morgan only nodded as her chubby hands grasped his now soaked shirt.

Pepper's eyes softened as she looked from her daughter up to Tony. They had certainly never referred to Peter as Morgan's brother, but he may as well be. It was more surprising that Morgan had picked up the term and attributed it to the kid without prompting.

"Baby, you can't see Peter right now. He's in school," Pepper tried to explain, rubbing her daughter's back once more.

"But I wanna see him now!" Morgan cried, glaring up at her parents for daring to keep her away from her favorite genetically enhanced teenager.

"Okay," Tony said, shifting Morgan so that he was holding her in front of him as he said, "Here's the deal, kid. If you can calm down, we will head to Peter's school so that you can see him _as soon as_ he gets out. It's only two more hours away. Can you do that for me?"

It took a few more minutes of cajoling and coaxing, but Morgan finally settled in to hiccupping cries instead of her previous shrieking and the Stark family quietly left the mall to fulfill their promise.

* * *

"Peter," Mr. Bitner stopped him on his way to the door of the classroom, instantly making him nervous.

"Uh, yeah, Mr. B?" Peter asked, nodding at Ned to go on without him. If he was about to get in trouble for something he didn't even know about, he didn't want an audience.

"I got this note for you during the quiz," Mr. Bitner explained, handing him what looked like a yellow detention slip, increasing Peter's nerves. Peter unfolded the note with trepidation as his chemistry teacher moved back to his desk.

 _Student:_ _Peter Parker_

 _Reason for detention:_ _Please report to the main office after seventh period._

 _S. Morita_

And that was it. A detention note that wasn't really a detention note, signed by his principal. Peter wasn't sure what he had done, but he knew that this couldn't mean anything good.

He took as much time as possible as he walked to his locker and collected his books and homework for the night, shoving them into his backpack before slinging it onto his shoulder. He contemplated several different outcomes as he made the trek to the main office of Midtown High. He only had a month left of school, and he couldn't imagine a meeting called at the end of the day on a _detention slip_ could signify anything good.

Which was why he was extremely surprised to walk into the office with apologies already on his lips to see the school's receptionist cooing over a baby with the Spanish teacher. Wait… he knew that baby.

"Morgan?" Peter asked in shock, causing said baby to look at him with wide, expectant eyes and grasping hands.

"Petta! Petta!"

"Hey, Iron Baby," Peter smiled at her cautiously as he moved to the counter where she was currently sitting, only now realizing that Pepper was standing beside her, one hand on her back to keep her steady as she smiled at Peter. "What's going on?"

"Oh," Pepper said, looking only a _little_ less put together than usual—something that tended to happen when dealing with cranky infants—and passed her daughter off into Peter's hands. "Someone had a traumatic experience and demanded that we bring her to see you as soon as possible."

"Awh," Peter cooed, grinning down at the suddenly much happier baby. "Is that true Morgan?"

Morgan grinned back before beginning to babble at him. "There was big, pink monsta, Petta. Monsta scary, so needed Brutha to scare monsta away. You good at that, Petta!"

Peter blinked down at her, trying to piece together her somewhat nonsensical story. "Uh, what?"

"You heard her, kid," Mr. Stark said, striding out of the principal's office with Principal Morita at his side, sending Peter a wink. "She's apparently scared of the big ol' Easter Bunny and needed her _big brother_ to comfort her."

Peter felt himself go red, unable to formulate a response, and was luckily saved by Miss Becht smiling at him from behind her computer and saying, "I didn't realize you had a sister, Peter."

 _So much for saving him_.

"Oh, I don't," Peter rushed to explain, pulling the collar of his shirt out of Morgan's mouth, much to her dismay, and shifting her to his other hip. "This is Mister and Missus Starks' daughter, Morgan."

"Yes, yes," Pepper said, having mercy on Peter. "We already introduced Morgan to everyone, didn't we sweetie?"

Morgan giggled happily, before going back to chattering at Peter, though he was still to confused by, well… everything to pay much attention. Not that Morgan minded.

"Peter just spends so much time with us for the _internship_ and Morgan has taken quite the liking to him," Tony explained, coming back around the desk to throw an arm around his wife and smile at his daughter lovingly.

"Oh," Mrs. Cortez chuckled, clapping her hands together. "That is just so cute."

"Yeah, it's really cute," Principal Morita sighed, looking at Peter with thinly veiled annoyance. "Parker, is it okay if you leave here with Mr. Stark? You're eighteen, so you can leave with whoever you want, but I still need to check with you before I let you leave here with them. School policy for anyone that comes in asking for students."

"Uh," Peter said, confusion only increasing by the second. "Yeah, I'm cool with leaving with them."

"Great," Principal Morita said, turning away. "Have a great weekend."

And with that, the Starks and Peter moved as one out of the school.

"What is all of this about, Mr. Stark?" Peter asked as they left the school, still holding onto the now much happier Morgan.

"We took the kid to the mall to see the Easter Bunny—a terrible idea, really, but anyway, she had a total meltdown and demanded we bring her to her 'brother.' So here we are," Tony reexplained, leading Peter to his parked car.

"But… I'm not—"

"Peter," Pepper interrupted gently with a pointed look at her dozing daughter, truly calm for the first time in two hours. "Are you so sure about that?"

Peter wasn't sure how to respond to that—he could admit that sometimes, including that precise moment, felt _something_ like a big brother to the youngest Stark, but he wasn't sure that he could really _call_ himself that. "I don't kn—"

"Petta," Morgan cut him off, perking up just enough to tug at his shirt to get his attention. "We go to park now?"

Peter chuckled. "I don't know, Mo. What did your mom and dad say?"

"Mom and dad said that we could do whatever she wanted as long as she stopped crying," Tony joked, nudging Peter as they walked across the parking lot. "As long as that's okay with you, Pete. If you have other plans, we're happy to drop you off on the way."

Peter shook his head, smiling at his mentor before looking back down at Morgan and saying, "Of course I'd love to go to the park with you."

Morgan's excited chattering about parks and Peter and monsters was cut off by possibly the worse person Peter could think of at the moment.

"Penis Parker!" Flash called, jogging over to him from the school doors, apparently getting out of class late. "I didn't realize you had a kid. Moving kind of fast, don't you think? We don't even graduate for another month!"

"Excuse me?"

Peter had temporarily forgotten that Mr. Stark was with him, and his mild annoyance at Flash's taunting became mild panic.

"Oh my god," Flash said, coming to a sudden, jerking halt in front of where they stood beside Mr. Stark's SUV (still stylish, but with all the safety and space that a baby required, or so he claimed). "You, you're—"

"Still waiting for an explanation," Mr. Stark replied in his Dad VoiceTM, crossing his arms and looking at Flash expectantly. Pepper only chuckled and shook her head, taking her daughter from Peter's arms and starting to buckle her into her car seat, leaving the confrontation to her overprotective husband.

Peter wished he could join her inside the safety of the car, but instead said, "Mr. Stark, this is Flash. Flash, this is Tony Stark."

"Yeah," Flash splutter, still looking at him with wide, disbelieving eyes. "I freakin' know who this is Parker. How do _you_ know him?"

"I told you," Peter muttered, crossing his arms and hugging them to his chest as he looked at the ground. "I've got that internship with Stark Industries."

"Yeah, but no one believed you!" Flash argued, though it was clearly pointless now.

"And how is that his problem, exactly, _Flash_? And I'm still waiting for you to explain to me what you just called Peter. In front of my _infant daughter_ , by the way."

"Wh—I didn't—I mean…" Flash floundered, unprepared for a confrontation, especially with an Avenger that drove a glorified minivan and apparently knew _Peter freakin' Parker_.

"Come on, Mr. Stark," Peter interrupted, turning around to put his bag into the car where Pepper and Morgan were still waiting. "We need to get to that thing."

"Right," Mr. Stark nodded, still sizing Flash up. "Great meeting you, Speedy. But next time you try to insult my kid, try to be a bit more creative. Or better yet, just stay away from him. I'd hate to have to come back here and explain simple civility to a punk teenager."

Peter watched with a gaping mouth as Tony patted Flash on the shoulder as he passed, getting into the driver's seat and waiting for Peter to get in before pulling out of the parking lot.

They spent several quite minutes on the road with Morgan snoozing in her car seat, exhausted after her tiring tantrum, and Peter incredibly awkward after that confrontation.

Had Mr. Stark really just called him his _kid_? _His_ kid?

"You didn't tell me you were having problems like that at school, Pete," Mr. Stark said, glancing at him in the rearview mirror as he drove.

Peter shrugged, unsure of how else to respond. "It's not a big deal, sir. You didn't have to do all of that."

"If people are bothering you, it's a big deal to me, kid. And I know I didn't have to. I also don't have to follow up on my promise to teach him some manners if he doesn't figure out how to behave like a civilized human being, but all you have to do is give me the word, Pete." Mr. Stark met his gaze in the mirror again, trying to convey his sincerity. "And I'll be there."

Peter smiled, unable to prevent the warm feeling that came with Mr. Stark's words. "You know, Mr. Stark, I think being a dad has made you kind of soft," he teased.

Mr. Stark scoffed and rolled his eyes while Pepper started laughing in the passenger seat. "You have no idea, kid."

A/N: The credit for the idea behind this chapter goes to Burt_Macklin_FBI_49 on AO3, who suggested this in a comment. Any prompts or ideas are always welcome (i.e. extremely encouraged, I'm not creative enough for this!), so please send me a message or ask if you feel so inclined!


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